1. Field of the Invention
The present invention relates to a hydrogen fuel feeding system for, for example, feeding a fuel gas containing hydrogen to a fuel cell and a fuel cell system that is provided with this hydrogen fuel feeding system.
2. Description of the Related Art
As a hydrogen fuel feeding system for feeding a fuel gas containing hydrogen to a fuel cell, a system for performing cyclic hydrocarbon reforming which alternately repeats a reforming process, to generate a hydrogen containing gas by reacting a hydrocarbon fuel with steam, and a regeneration process, for raising a catalyst temperature that is lowered in the reforming process, has been known (for example, refer to US Patent Application Publication No. 2004/0170559A). The system described in this document is provided with a pair of reactors that can perform the reforming process and the regeneration process. This system continuously feeds a hydrogen containing gas to a fuel cell by performing batch hydrocarbon reforming, where one reactor performs the reforming process while the other reactor performs the regeneration process. After the reforming process, shift reaction and hydrogen separation are performed to feed a hydrogen-rich fuel to a fuel cell. Also, purge gas passed through a hydrogen separator is used as a gas for regeneration (a fuel) of the regeneration process without being fed to the fuel cell. A cathode-off gas (an oxygen-containing gas) of the fuel cell is introduced into the reactor performing the regeneration process for combusting the purge gas so as to raise a catalyst to a temperature at which the reforming process can be performed, by combustion of the purge gas.
However, according to the above-described conventional art, the processing of the gas remaining in the reactor upon switching from the reforming process to the regeneration process, or upon switching from the regeneration process to the reforming process has not been considered.